National Center for Emerging and Zoonotic Infectious Diseases

Babies, and Biofilms: An Outbreak of Pseudomonas aeruginosa in a neonatal intensive care unit

Division for Healthcare Quality Promotion

Centers for Disease Control and Prevention

TSICP

April 2018

Game Plan

▪ Pseudomonas basics

▪ NICU outbreak investigation

▪ NICU water quality

▪ Take-home points

Pseudomonas aeruginosa (PA)

▪ An important cause of serious healthcare-associated infections (HAI)

▪ Water-associated pathogen

▪ Common in healthcare environments

Matt Arduino, CDC

Water Basics: Biofilms

▪ Group of microorganisms that stick together

– Many different organisms

– Many different strains of the same organism

▪ Surrounded by a slimy extracellular matrix

– Protects bugs from antimicrobials

– Ability to grow at extreme temperatures

– Require higher levels of disinfectants

▪ Can form on almost any surface in an aqueous or humid environment

1 1

0 0

2 2

0

2

00

1

2

3

4

Cas

e C

ou

nt

NICU Closure 1 Enhanced Water Treatment

NICU ReopensContinuous enhanced

water treatment

NICU Re-closureEpi-Aid requested

Transmission of PA, March –October 2016

Eight cases of Pseudomonas aeruginosa in a neonatal intensive care unit (NICU)

Welcome to the NICU

▪ Incubator: protect baby from fluctuations in humidity

▪ Breast pump: maintain nutrition

Objectives of Investigation

▪ Define outbreak scope

▪ Identify Pseudomonas transmission risks related to water exposures

▪ Review water management practices and water sampling results

▪ Provide recommendations to decrease risk of further transmission

Case Definition

▪ Clinical or surveillance culture positive for Pseudomonas aeruginosa

▪ Patient receiving care in the NICU at Hospital A at the time of positive culture collection

▪ March 2016 to October 2016

Records Review and Interviews

▪ Reviewed laboratory and medical records

▪ Interviewed

– Nursing

– Facilities management

– Environmental services

– Respiratory therapy

▪ Hospital water management

• Supplemental chlorination

• Point-of-use filters

• Water quality testing

▪ Potential water exposures in the NICU

• Sink use

• Breast milk preparation

• Reprocessing of reusable breast pump equipment

• Water used in isolette humidifier reservoirs

Hospital Water in the NICU: Management and Use

Laboratory Methods

▪ Targeted environmental sampling of equipment, breast milk, and surfaces

▪ Sampling of post-filter tap water from NICU sinks

▪ Comparison of clinical and environmental isolates using pulsed-field gel electrophoresis (PFGE)

Case Investigation ResultsCharacteristic n/N (%)

Gestational age(weeks)

Median (range)27 (24-31)

Female 3/8 (37.5)On respiratory support 7/7 (100)

Breastmilk 2/2 (100)Born in Hospital A 7/8 (87.5)

InfectedColonized

4/8 (50)4/8 (50)

Deaths 2/8 (25)

Water Sampling ResultsPre-Intervention Post-Intervention

HPC (colony-forming units / mL)Pseudomonas Identified

(n=4 sinks) HPC (CFU/10mL)Pseudomonas Identified (n=3

sinks)Bulk water 3000-6000 Yes <1 – 3 Yes

500 CFU/mL

Nutrition Prep Area

Fridge

Lactation Room

Lactation Pumps

Breast Milk

Sink 1Sink 10

Sink8

Sink 9

Sink 2

Sink 6

Sink 5

Sink 3

Bed

Bed

Bed

Bed

BedBedBed

Bed

Bed

Bed

Bed

BedBedBedBed

NICU MAP

▪ Splashing

▪ Tap water for refilling humidifier reservoirs

▪ Cleaning reusable breast pump equipment

Infection Prevention and Control Practices and Water Exposures

municipal water treatment hospital water supplyNICU sinks

Potential Transmission Pathways

sink 6 tap waterpatient CNICU staff bathroom

sink tap waterpatient D

..

UnrelatedUnrelated

UnrelatedUnrelated

Unrelated

relatednessdescription10

0

percent similarity

Fridge

Lactation Room

Lactation Pumps

Breast Milk

sink 5 water, post-filter

sink 6 water, post-filtersink 10 water, post-filter

.

.

.

.

.

.CLUSTER C

sink 2 water, pre-interventionpatient Asink 1 water, pre-intervention

CLUSTER A

patient Bsink 3 water, pre-intervention CLUSTER B

patient F

.

.

.

.breast milk

patient E CLUSTER D

breast milk.

.

.

.CLUSTER E

PFGE Results

82.4

80.0

58.8

54.6

68.3

63.4

94.4

87.4

75.3

59.0

52.3

A

A

B

C

C

C

D

E

Conclusions

▪ NICU outbreak of Pseudomonas• contamination of hospital water

system• use of water in the NICU

▪ Multiple potential transmission pathways identified

▪ Improved water quality alone did not eliminate transmission

Investigation Challenges

▪ Highly-charged investigation

▪ NICU closed

Take-home Points

An Unhappy Combo

Water Supply

Vulnerable Population

Employ a Team Approach

▪ Infection prevention and control (IPC)

▪ Hospital epidemiologist

▪ Laboratory

▪ Risk management

▪ Nurses

▪ Surgeons

▪ Physicians

▪ Respiratory therapists

▪ Occupational health

▪ Building engineers

▪ Water consultant

▪ Facilities management

Water Supply Vulnerable Population

Infection Control Assessments

▪ Commonly observed practices:

– Hand hygiene

– Surgical procedures

– Use of contact precautions

– Medication preparation

– Respiratory therapy

– Environmental cleaning

▪ How could water or its vapor be a source of transmission?

Environmental Assessment

▪ Don’t jump to this without first exploring epidemiology of the outbreak

▪ Organism of interest will also guide type of sampling

▪ Only a snapshot of what is happening

▪ Understand limitations

– Most clinical labs are not able to do this

– Require expertise to execute

– Expensive

What will you do with the results?

Water Sampling: Microbiology

➢ Especially helpful with gram-negative rods and nontuberculous mycobacteria

▪ Culture

▪ Heterotrophic plate counts (HPC)

▪ Challenges:

– Biofilm sloughing can cause levels in the water to fluctuate over time

– Residual disinfectant in tap water can decrease yield

Water Sampling: Biochemical

▪ Residual disinfectant levels

▪ Free ammonia

▪ Nitrite/Nitrates

ChloraminesAmmonia Nitrites

Nitrates

Nitrifying Bacteria

Water Basics: Water Distribution Systems

Levels of:• Microorganism• Residual disinfectant

Treatment Plant

?

Water Basics: Amplification

▪ Complex systems

▪ Low Flow

▪ “Dead legs” or areas with stagnant water

▪ Water temperature

▪ Loss of disinfectant residual

Search for Water Exposures

Challenges for Water Sampling & Testing

▪ Large volume water samples required

▪ Diversity of microbes in water

▪ May need to remove competing bacteria

▪ Multiple species grow within the same biofilm

▪ Lab samples only a few colonies for identification after isolation

Surface Sampling

▪ Consider possible transmission pathways

– Mobile medical equipment?

– High touch room surfaces?

▪ Challenges:

– Surface contamination not uniform

– Yield can be low at baseline, especially if residual disinfectant on surface

Apply Environmental Testing Judiciously

▪ Environmental testing driven by epidemiology findings

▪ Understand the bug

▪ Interpreting lab results can be challenging

▪ What to do with a positive result?

Consider Multiple Interventions

▪ “Pre-faucet”

– Municipal supply

– Shock treatment

– Supplemental disinfection

– Flushing protocols

▪ “Post-faucet”

– Educate

– Improve IPC

– Limit source exposure

– Aerosol-generating activities

▪ Water filters

▪ Replace sink fixtures

Remaining Questions

▪ Are existing CDC water management guidelines sufficient or applicable for all water-associated organisms?

▪ How appropriate is the EPA threshold for municipal water systems for vulnerable healthcare populations?

▪ How can we better understand the relationship between bacterial contamination levels and risk of transmission in healthcare environments?

For more information please contact Centers for Disease Control and Prevention

1600 Clifton Road NE, Atlanta, GA 30333

Telephone: 1-800-CDC-INFO (232-4636)/TTY: 1-888-232-6348

Visit: www.cdc.gov | Contact CDC at: 1-800-CDC-INFO or www.cdc.gov/info

The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.

Questions ?

Thank you:Mark WengKim SkrobacekState A Health Department